DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES
This project is directed at an investigation of catalytic NO{sub x} reduction mechanisms on coal-derived, activated carbon supports at low temperatures. Promoted carbon systems offer some potentially significant advantages for heterogeneous NO{sub x} reduction. These include: low cost; high activity at low temperatures, which minimizes carbon loss; oxygen resistance; and a support material which can be engineered with respect to porosity, transport and catalyst dispersion characteristics. During the reporting period, TPD studies were conducted following steady-state reaction in NO/CO mixtures in helium. From these studies, the following points have been concluded: (1) The total amount of CO and N{sub 2} evolved following reaction in NO increases with reaction temperature. The TPD spectra are skewed to high temperatures, indicating more stable surface complexes with high desorption activation energies. (2) The total amount of CO evolved following exposure of the char sample to CO at reaction temperatures decreases with reaction temperature, similar to chemisorption behavior. The CO TPD spectra are shifted to lower temperatures, indicating more labile oxygen surface complexes with lower desorption activation energies. (3) The total amount of CO evolved following reaction in NO/CO mixtures decreases with reaction temperature, while the evolved N{sub 2} still increases with reaction temperature. The CO TPD spectra appear more similar to those obtained following exposure to pure CO, while the N{sub 2} TPD spectra are more similar to those obtained followed reaction in just CO. Based on the preceding observations, a simple mechanism was formulated whereby two different types of surface complexes are formed by NO and CO; the former are more stable, and the latter more labile. This produces two parallel routes for the NO-carbon reaction: (a) the C(O) complexes formed directly by NO desorb as CO; and (b) The C(CO) complexes formed by CO, react with NO to produce CO{sub 2}. This mechanism is consistent with most of what is known about the NO/CO-carbon reaction system. During the next reporting period the packed bed reactor system will be used investigate the NO and NO/CO reactions systems over potassium-promoted resin char samples. These studies will include steady-state reaction rate measurements, as well as temperature programmed desorption studies.
- Research Organization:
- Federal Energy Technology Center Morgantown (FETC-MGN), Morgantown, WV (United States); Federal Energy Technology Center Pittsburgh (FETC-PGH), Pittsburgh, PA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- FG26-97FT97267
- OSTI ID:
- 783590
- Report Number(s):
- FG26-97FT97267-04; TRN: AH200128%%85
- Resource Relation:
- Other Information: PBD: 24 Jul 2000
- Country of Publication:
- United States
- Language:
- English
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DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES
DEVELOPMENT OF HIGH ACTIVITY, CATALYTIC SYSTEMS FOR NOx REDUCTION